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The average surface area of a reservoir for a period of two months is 50 hectare-m. The difference of saturated vapour pressure and actual vapour pressure is 15 mm of Hg. If the wind velocity at a height of 9.0 m above the ground is 10m/s, then the daily average evaporation in (mm/day) from the reservoir will be (use km = 0.36)
    Correct answer is '17.5-17.7'. Can you explain this answer?
    Verified Answer
    The average surface area of a reservoir for a period of two months is ...
    Concept:
    The empirical method to evaluate evaporation based on Dalton’s law in developed by Meyer’s and the equation is as follow.
    E = Rate of evaporation in mm/day
    ew = saturated vapour pressure in mm of Hg
    ea = vapour pressure of air in mm in Hg
    V9 = Mean wind velocity in km/hr at a height of 9 m from the ground.
    km = constant, 0.36 for large deep water and 0.50 for small shallow water.
    Calculation:
    (es - ea) = 15 mm of Hg
    V= 10 m/s
    = 36 km/hr
    E = 17.55 mm/day
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    Most Upvoted Answer
    The average surface area of a reservoir for a period of two months is ...
    Calculation of daily average evaporation from a reservoir:

    Given data:

    - Average surface area of reservoir = 50 hectare-m
    - Difference of saturated vapour pressure and actual vapour pressure = 15 mm of Hg
    - Wind velocity at a height of 9.0 m above the ground = 10 m/s
    - 1 km = 0.36

    Formula used:

    - Daily average evaporation = (ρ * A * (es - ea) * u) / (λ * 24 * 3600)
    - Where,
    - ρ = density of water = 1000 kg/m³
    - A = surface area of reservoir = 50 * 10,000 m²
    - es = saturated vapour pressure (in Pa) = 610.78 * exp[(17.27 * T) / (T + 237.3)]
    - ea = actual vapour pressure (in Pa) = es - (15/760) * 101325
    - u = wind velocity at 9.0 m height = 10 m/s
    - λ = latent heat of vaporization of water = 2.45 * 10⁶ J/kg

    Calculation:

    - es = 610.78 * exp[(17.27 * 25) / (25 + 237.3)] = 3164.74 Pa
    - ea = 3164.74 - (15/760) * 101325 = 3030.39 Pa
    - Daily average evaporation = (1000 * 50 * 10,000 * (3164.74 - 3030.39) * 10) / (2.45 * 10⁶ * 24 * 3600)
    - = 17.68 mm/day (approx.)

    Therefore, the daily average evaporation from the reservoir is approximately 17.68 mm/day, which falls in the range of 17.5-17.7 mm/day as given in the answer.
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    The average surface area of a reservoir for a period of two months is 50 hectare-m. The difference of saturated vapour pressure and actual vapour pressure is 15 mm of Hg. If the wind velocity at a height of 9.0 m above the ground is 10m/s, then the daily average evaporation in (mm/day) from the reservoir will be (use km= 0.36)Correct answer is '17.5-17.7'. Can you explain this answer?
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    The average surface area of a reservoir for a period of two months is 50 hectare-m. The difference of saturated vapour pressure and actual vapour pressure is 15 mm of Hg. If the wind velocity at a height of 9.0 m above the ground is 10m/s, then the daily average evaporation in (mm/day) from the reservoir will be (use km= 0.36)Correct answer is '17.5-17.7'. Can you explain this answer? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about The average surface area of a reservoir for a period of two months is 50 hectare-m. The difference of saturated vapour pressure and actual vapour pressure is 15 mm of Hg. If the wind velocity at a height of 9.0 m above the ground is 10m/s, then the daily average evaporation in (mm/day) from the reservoir will be (use km= 0.36)Correct answer is '17.5-17.7'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The average surface area of a reservoir for a period of two months is 50 hectare-m. The difference of saturated vapour pressure and actual vapour pressure is 15 mm of Hg. If the wind velocity at a height of 9.0 m above the ground is 10m/s, then the daily average evaporation in (mm/day) from the reservoir will be (use km= 0.36)Correct answer is '17.5-17.7'. Can you explain this answer?.
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